In an interview about the book – a collection of insights from his time in the SEALs and at his leadership consulting firm, Echelon Front – Willink told Business Insider why he thinks it’s important to bring discipline to your diet.

“I would say there are some foods that I strongly recommend that you do not eat,” he said. “No. 1 on that list, I believe, is doughnuts. Comfort food. Zero value. Don’t eat them.”

While doughnuts come in plenty of varieties, the base of fried dough is high in fat, about half of which is saturated.

High amounts of saturated fat have been linked to heart disease, and one doughnut can account for about a third of the recommended daily intake.

Doughnuts are one of the ubiquitous office foods that you probably shouldn’t be eating, at least not regularly, and it’s why Willink has made it a rule for himself to never accept free snacks.

When people want to be nice, especially in office settings, they’ll bring in some comfort food to their break rooms, he said, but “they’re actually sabotaging the health of their coworkers.”

“So what do you do in those situations?” he said. “It’s really easy: don’t eat. Don’t eat the doughnuts. Don’t eat the bagels. Don’t eat the slab of pizza.

“We have food all around us all the time, and if we haven’t eaten for three hours we think we’re starving,” he said. “You’re not starving – human beings can go for 30 days without food.”

Either get something healthy or ignore the desire to consume a lump of fat and carbohydrates that will spike your blood sugar, he said.